President Donald Trump told Fox News on Friday that Michael Flynn was “already approved by the Obama administration at the highest level” when he was hired to serve as national security adviser in January.

Flynn, who headed the Defence Intelligence Agency from 2012 to 2014, came under renewed scrutiny earlier this week when the House Oversight Committee revealed that he did not disclose his payments from Russia’s state-owned news agency, Russia Today, when he was renewing his security clearance in January 2016.

Flynn also lobbied on behalf of a Turkish businessman with ties to the country’s government between August and November of 2016, but he did not register as a foreign agent with the Justice Department until earlier this year.

The White House has said that what Flynn did as a private citizen, after he retired from the DIA and before he was hired by the Trump administration, was not its concern. But Trump has faced questions about why Flynn, who was forced to step down as national security adviser after only 24 days, was not more thoroughly vetted for potential conflicts of interest before he was brought into the White House.

“When he left, when he resigned, you said that he was treated horribly and that you felt badly about that,” Fox News anchor Martha MacCallum asked Trump in an interview Friday, according to excerpts released by the network. “Given what we are now seeing, on the payments from Turkey and Russia, would you stand by that comment?”

Trump replied that while he does feel badly, Flynn “was approved by the Obama administration at the highest level.”

“And when they say we didn’t vet, well Obama I guess didn’t vet, because he was approved at the highest level of security by the Obama administration,” Trump said. “So when he came into our administration, for a short period of time, he came in, he was already approved by the Obama administration and he had years left on that approval.”

Trump appeared to be doubling down on a talking point about Flynn’s controversies that was first articulated on Thursday by White House press secretary Sean Spicer.

“When General Flynn came into the White House, he had an active security clearance that was issued during the Obama administration with all the information that’s being discussed that occurred in 2015,” Spicer told reporters. “Why would you rerun a background check on someone who was the head of the Defence Intelligence Agency that had and did maintain a high-level security clearance?”

Flynn’s security clearance was reauthorized in January 2016 — presumably due to his role managing Flynn Intel Group — which means he wouldn’t have had to renew it until at least 2021.

Still, many national security and intelligence experts argue that, in light of Flynn’s lobbying work throughout 2016 and the fact that he was pushed out by the Obama administration in 2014, he should have been subject to more scrutiny before he was elevated to such a high-level national-security position at the White House.

“Flynn would have had to submit updated forms covering the period of time since his last [security clearance] investigation,” said Susan Hennessey, a fellow at the Brookings Institution and former attorney at the National Security Agency. “There is always a re-investigation after being out of access.”

Rep. Elijah Cummings, the ranking Democrat on the House Oversight Committee, said earlier this week that while Flynn’s negligence on his security-clearance forms could be punished by up to five years in prison, that decision was not up to the committee. Cummings called on the Defence Department in early February to investigate whether Flynn had violated the Emoluments Clause by accepting the $US33,000 payment from RT.

Cummings said in a statement on Thursday that the documents “raise grave questions about why General Flynn concealed the payments he received from foreign sources after he was warned explicitly by the Pentagon.”

“Our next step is to get the documents we are seeking from the White House so we can complete our investigation,” he added.